diff options
Diffstat (limited to 'Documentation/ia64')
| -rw-r--r-- | Documentation/ia64/IRQ-redir.txt | 69 | ||||
| -rw-r--r-- | Documentation/ia64/README | 43 | ||||
| -rw-r--r-- | Documentation/ia64/efirtc.txt | 128 | ||||
| -rw-r--r-- | Documentation/ia64/fsys.txt | 286 | ||||
| -rw-r--r-- | Documentation/ia64/serial.txt | 144 |
5 files changed, 670 insertions, 0 deletions
diff --git a/Documentation/ia64/IRQ-redir.txt b/Documentation/ia64/IRQ-redir.txt new file mode 100644 index 00000000000..f7bd7226128 --- /dev/null +++ b/Documentation/ia64/IRQ-redir.txt @@ -0,0 +1,69 @@ +IRQ affinity on IA64 platforms +------------------------------ + 07.01.2002, Erich Focht <efocht@ess.nec.de> + + +By writing to /proc/irq/IRQ#/smp_affinity the interrupt routing can be +controlled. The behavior on IA64 platforms is slightly different from +that described in Documentation/IRQ-affinity.txt for i386 systems. + +Because of the usage of SAPIC mode and physical destination mode the +IRQ target is one particular CPU and cannot be a mask of several +CPUs. Only the first non-zero bit is taken into account. + + +Usage examples: + +The target CPU has to be specified as a hexadecimal CPU mask. The +first non-zero bit is the selected CPU. This format has been kept for +compatibility reasons with i386. + +Set the delivery mode of interrupt 41 to fixed and route the +interrupts to CPU #3 (logical CPU number) (2^3=0x08): + echo "8" >/proc/irq/41/smp_affinity + +Set the default route for IRQ number 41 to CPU 6 in lowest priority +delivery mode (redirectable): + echo "r 40" >/proc/irq/41/smp_affinity + +The output of the command + cat /proc/irq/IRQ#/smp_affinity +gives the target CPU mask for the specified interrupt vector. If the CPU +mask is preceded by the character "r", the interrupt is redirectable +(i.e. lowest priority mode routing is used), otherwise its route is +fixed. + + + +Initialization and default behavior: + +If the platform features IRQ redirection (info provided by SAL) all +IO-SAPIC interrupts are initialized with CPU#0 as their default target +and the routing is the so called "lowest priority mode" (actually +fixed SAPIC mode with hint). The XTP chipset registers are used as hints +for the IRQ routing. Currently in Linux XTP registers can have three +values: + - minimal for an idle task, + - normal if any other task runs, + - maximal if the CPU is going to be switched off. +The IRQ is routed to the CPU with lowest XTP register value, the +search begins at the default CPU. Therefore most of the interrupts +will be handled by CPU #0. + +If the platform doesn't feature interrupt redirection IOSAPIC fixed +routing is used. The target CPUs are distributed in a round robin +manner. IRQs will be routed only to the selected target CPUs. Check +with + cat /proc/interrupts + + + +Comments: + +On large (multi-node) systems it is recommended to route the IRQs to +the node to which the corresponding device is connected. +For systems like the NEC AzusA we get IRQ node-affinity for free. This +is because usually the chipsets on each node redirect the interrupts +only to their own CPUs (as they cannot see the XTP registers on the +other nodes). + diff --git a/Documentation/ia64/README b/Documentation/ia64/README new file mode 100644 index 00000000000..aa17f2154cb --- /dev/null +++ b/Documentation/ia64/README @@ -0,0 +1,43 @@ + Linux kernel release 2.4.xx for the IA-64 Platform + + These are the release notes for Linux version 2.4 for IA-64 + platform. This document provides information specific to IA-64 + ONLY, to get additional information about the Linux kernel also + read the original Linux README provided with the kernel. + +INSTALLING the kernel: + + - IA-64 kernel installation is the same as the other platforms, see + original README for details. + + +SOFTWARE REQUIREMENTS + + Compiling and running this kernel requires an IA-64 compliant GCC + compiler. And various software packages also compiled with an + IA-64 compliant GCC compiler. + + +CONFIGURING the kernel: + + Configuration is the same, see original README for details. + + +COMPILING the kernel: + + - Compiling this kernel doesn't differ from other platform so read + the original README for details BUT make sure you have an IA-64 + compliant GCC compiler. + +IA-64 SPECIFICS + + - General issues: + + o Hardly any performance tuning has been done. Obvious targets + include the library routines (IP checksum, etc.). Less + obvious targets include making sure we don't flush the TLB + needlessly, etc. + + o SMP locks cleanup/optimization + + o IA32 support. Currently experimental. It mostly works. diff --git a/Documentation/ia64/efirtc.txt b/Documentation/ia64/efirtc.txt new file mode 100644 index 00000000000..ede2c1e51cd --- /dev/null +++ b/Documentation/ia64/efirtc.txt @@ -0,0 +1,128 @@ +EFI Real Time Clock driver +------------------------------- +S. Eranian <eranian@hpl.hp.com> +March 2000 + +I/ Introduction + +This document describes the efirtc.c driver has provided for +the IA-64 platform. + +The purpose of this driver is to supply an API for kernel and user applications +to get access to the Time Service offered by EFI version 0.92. + +EFI provides 4 calls one can make once the OS is booted: GetTime(), +SetTime(), GetWakeupTime(), SetWakeupTime() which are all supported by this +driver. We describe those calls as well the design of the driver in the +following sections. + +II/ Design Decisions + +The original ideas was to provide a very simple driver to get access to, +at first, the time of day service. This is required in order to access, in a +portable way, the CMOS clock. A program like /sbin/hwclock uses such a clock +to initialize the system view of the time during boot. + +Because we wanted to minimize the impact on existing user-level apps using +the CMOS clock, we decided to expose an API that was very similar to the one +used today with the legacy RTC driver (driver/char/rtc.c). However, because +EFI provides a simpler services, not all all ioctl() are available. Also +new ioctl()s have been introduced for things that EFI provides but not the +legacy. + +EFI uses a slightly different way of representing the time, noticeably +the reference date is different. Year is the using the full 4-digit format. +The Epoch is January 1st 1998. For backward compatibility reasons we don't +expose this new way of representing time. Instead we use something very +similar to the struct tm, i.e. struct rtc_time, as used by hwclock. +One of the reasons for doing it this way is to allow for EFI to still evolve +without necessarily impacting any of the user applications. The decoupling +enables flexibility and permits writing wrapper code is ncase things change. + +The driver exposes two interfaces, one via the device file and a set of +ioctl()s. The other is read-only via the /proc filesystem. + +As of today we don't offer a /proc/sys interface. + +To allow for a uniform interface between the legacy RTC and EFI time service, +we have created the include/linux/rtc.h header file to contain only the +"public" API of the two drivers. The specifics of the legacy RTC are still +in include/linux/mc146818rtc.h. + + +III/ Time of day service + +The part of the driver gives access to the time of day service of EFI. +Two ioctl()s, compatible with the legacy RTC calls: + + Read the CMOS clock: ioctl(d, RTC_RD_TIME, &rtc); + + Write the CMOS clock: ioctl(d, RTC_SET_TIME, &rtc); + +The rtc is a pointer to a data structure defined in rtc.h which is close +to a struct tm: + +struct rtc_time { + int tm_sec; + int tm_min; + int tm_hour; + int tm_mday; + int tm_mon; + int tm_year; + int tm_wday; + int tm_yday; + int tm_isdst; +}; + +The driver takes care of converting back an forth between the EFI time and +this format. + +Those two ioctl()s can be exercised with the hwclock command: + +For reading: +# /sbin/hwclock --show +Mon Mar 6 15:32:32 2000 -0.910248 seconds + +For setting: +# /sbin/hwclock --systohc + +Root privileges are required to be able to set the time of day. + +IV/ Wakeup Alarm service + +EFI provides an API by which one can program when a machine should wakeup, +i.e. reboot. This is very different from the alarm provided by the legacy +RTC which is some kind of interval timer alarm. For this reason we don't use +the same ioctl()s to get access to the service. Instead we have +introduced 2 news ioctl()s to the interface of an RTC. + +We have added 2 new ioctl()s that are specific to the EFI driver: + + Read the current state of the alarm + ioctl(d, RTC_WKLAM_RD, &wkt) + + Set the alarm or change its status + ioctl(d, RTC_WKALM_SET, &wkt) + +The wkt structure encapsulates a struct rtc_time + 2 extra fields to get +status information: + +struct rtc_wkalrm { + + unsigned char enabled; /* =1 if alarm is enabled */ + unsigned char pending; /* =1 if alarm is pending */ + + struct rtc_time time; +} + +As of today, none of the existing user-level apps supports this feature. +However writing such a program should be hard by simply using those two +ioctl(). + +Root privileges are required to be able to set the alarm. + +V/ References. + +Checkout the following Web site for more information on EFI: + +http://developer.intel.com/technology/efi/ diff --git a/Documentation/ia64/fsys.txt b/Documentation/ia64/fsys.txt new file mode 100644 index 00000000000..28da181f996 --- /dev/null +++ b/Documentation/ia64/fsys.txt @@ -0,0 +1,286 @@ +-*-Mode: outline-*- + + Light-weight System Calls for IA-64 + ----------------------------------- + + Started: 13-Jan-2003 + Last update: 27-Sep-2003 + + David Mosberger-Tang + <davidm@hpl.hp.com> + +Using the "epc" instruction effectively introduces a new mode of +execution to the ia64 linux kernel. We call this mode the +"fsys-mode". To recap, the normal states of execution are: + + - kernel mode: + Both the register stack and the memory stack have been + switched over to kernel memory. The user-level state is saved + in a pt-regs structure at the top of the kernel memory stack. + + - user mode: + Both the register stack and the kernel stack are in + user memory. The user-level state is contained in the + CPU registers. + + - bank 0 interruption-handling mode: + This is the non-interruptible state which all + interruption-handlers start execution in. The user-level + state remains in the CPU registers and some kernel state may + be stored in bank 0 of registers r16-r31. + +In contrast, fsys-mode has the following special properties: + + - execution is at privilege level 0 (most-privileged) + + - CPU registers may contain a mixture of user-level and kernel-level + state (it is the responsibility of the kernel to ensure that no + security-sensitive kernel-level state is leaked back to + user-level) + + - execution is interruptible and preemptible (an fsys-mode handler + can disable interrupts and avoid all other interruption-sources + to avoid preemption) + + - neither the memory-stack nor the register-stack can be trusted while + in fsys-mode (they point to the user-level stacks, which may + be invalid, or completely bogus addresses) + +In summary, fsys-mode is much more similar to running in user-mode +than it is to running in kernel-mode. Of course, given that the +privilege level is at level 0, this means that fsys-mode requires some +care (see below). + + +* How to tell fsys-mode + +Linux operates in fsys-mode when (a) the privilege level is 0 (most +privileged) and (b) the stacks have NOT been switched to kernel memory +yet. For convenience, the header file <asm-ia64/ptrace.h> provides +three macros: + + user_mode(regs) + user_stack(task,regs) + fsys_mode(task,regs) + +The "regs" argument is a pointer to a pt_regs structure. The "task" +argument is a pointer to the task structure to which the "regs" +pointer belongs to. user_mode() returns TRUE if the CPU state pointed +to by "regs" was executing in user mode (privilege level 3). +user_stack() returns TRUE if the state pointed to by "regs" was +executing on the user-level stack(s). Finally, fsys_mode() returns +TRUE if the CPU state pointed to by "regs" was executing in fsys-mode. +The fsys_mode() macro is equivalent to the expression: + + !user_mode(regs) && user_stack(task,regs) + +* How to write an fsyscall handler + +The file arch/ia64/kernel/fsys.S contains a table of fsyscall-handlers +(fsyscall_table). This table contains one entry for each system call. +By default, a system call is handled by fsys_fallback_syscall(). This +routine takes care of entering (full) kernel mode and calling the +normal Linux system call handler. For performance-critical system +calls, it is possible to write a hand-tuned fsyscall_handler. For +example, fsys.S contains fsys_getpid(), which is a hand-tuned version +of the getpid() system call. + +The entry and exit-state of an fsyscall handler is as follows: + +** Machine state on entry to fsyscall handler: + + - r10 = 0 + - r11 = saved ar.pfs (a user-level value) + - r15 = system call number + - r16 = "current" task pointer (in normal kernel-mode, this is in r13) + - r32-r39 = system call arguments + - b6 = return address (a user-level value) + - ar.pfs = previous frame-state (a user-level value) + - PSR.be = cleared to zero (i.e., little-endian byte order is in effect) + - all other registers may contain values passed in from user-mode + +** Required machine state on exit to fsyscall handler: + + - r11 = saved ar.pfs (as passed into the fsyscall handler) + - r15 = system call number (as passed into the fsyscall handler) + - r32-r39 = system call arguments (as passed into the fsyscall handler) + - b6 = return address (as passed into the fsyscall handler) + - ar.pfs = previous frame-state (as passed into the fsyscall handler) + +Fsyscall handlers can execute with very little overhead, but with that +speed comes a set of restrictions: + + o Fsyscall-handlers MUST check for any pending work in the flags + member of the thread-info structure and if any of the + TIF_ALLWORK_MASK flags are set, the handler needs to fall back on + doing a full system call (by calling fsys_fallback_syscall). + + o Fsyscall-handlers MUST preserve incoming arguments (r32-r39, r11, + r15, b6, and ar.pfs) because they will be needed in case of a + system call restart. Of course, all "preserved" registers also + must be preserved, in accordance to the normal calling conventions. + + o Fsyscall-handlers MUST check argument registers for containing a + NaT value before using them in any way that could trigger a + NaT-consumption fault. If a system call argument is found to + contain a NaT value, an fsyscall-handler may return immediately + with r8=EINVAL, r10=-1. + + o Fsyscall-handlers MUST NOT use the "alloc" instruction or perform + any other operation that would trigger mandatory RSE + (register-stack engine) traffic. + + o Fsyscall-handlers MUST NOT write to any stacked registers because + it is not safe to assume that user-level called a handler with the + proper number of arguments. + + o Fsyscall-handlers need to be careful when accessing per-CPU variables: + unless proper safe-guards are taken (e.g., interruptions are avoided), + execution may be pre-empted and resumed on another CPU at any given + time. + + o Fsyscall-handlers must be careful not to leak sensitive kernel' + information back to user-level. In particular, before returning to + user-level, care needs to be taken to clear any scratch registers + that could contain sensitive information (note that the current + task pointer is not considered sensitive: it's already exposed + through ar.k6). + + o Fsyscall-handlers MUST NOT access user-memory without first + validating access-permission (this can be done typically via + probe.r.fault and/or probe.w.fault) and without guarding against + memory access exceptions (this can be done with the EX() macros + defined by asmmacro.h). + +The above restrictions may seem draconian, but remember that it's +possible to trade off some of the restrictions by paying a slightly +higher overhead. For example, if an fsyscall-handler could benefit +from the shadow register bank, it could temporarily disable PSR.i and +PSR.ic, switch to bank 0 (bsw.0) and then use the shadow registers as +needed. In other words, following the above rules yields extremely +fast system call execution (while fully preserving system call +semantics), but there is also a lot of flexibility in handling more +complicated cases. + +* Signal handling + +The delivery of (asynchronous) signals must be delayed until fsys-mode +is exited. This is acomplished with the help of the lower-privilege +transfer trap: arch/ia64/kernel/process.c:do_notify_resume_user() +checks whether the interrupted task was in fsys-mode and, if so, sets +PSR.lp and returns immediately. When fsys-mode is exited via the +"br.ret" instruction that lowers the privilege level, a trap will +occur. The trap handler clears PSR.lp again and returns immediately. +The kernel exit path then checks for and delivers any pending signals. + +* PSR Handling + +The "epc" instruction doesn't change the contents of PSR at all. This +is in contrast to a regular interruption, which clears almost all +bits. Because of that, some care needs to be taken to ensure things +work as expected. The following discussion describes how each PSR bit +is handled. + +PSR.be Cleared when entering fsys-mode. A srlz.d instruction is used + to ensure the CPU is in little-endian mode before the first + load/store instruction is executed. PSR.be is normally NOT + restored upon return from an fsys-mode handler. In other + words, user-level code must not rely on PSR.be being preserved + across a system call. +PSR.up Unchanged. +PSR.ac Unchanged. +PSR.mfl Unchanged. Note: fsys-mode handlers must not write-registers! +PSR.mfh Unchanged. Note: fsys-mode handlers must not write-registers! +PSR.ic Unchanged. Note: fsys-mode handlers can clear the bit, if needed. +PSR.i Unchanged. Note: fsys-mode handlers can clear the bit, if needed. +PSR.pk Unchanged. +PSR.dt Unchanged. +PSR.dfl Unchanged. Note: fsys-mode handlers must not write-registers! +PSR.dfh Unchanged. Note: fsys-mode handlers must not write-registers! +PSR.sp Unchanged. +PSR.pp Unchanged. +PSR.di Unchanged. +PSR.si Unchanged. +PSR.db Unchanged. The kernel prevents user-level from setting a hardware + breakpoint that triggers at any privilege level other than 3 (user-mode). +PSR.lp Unchanged. +PSR.tb Lazy redirect. If a taken-branch trap occurs while in + fsys-mode, the trap-handler modifies the saved machine state + such that execution resumes in the gate page at + syscall_via_break(), with privilege level 3. Note: the + taken branch would occur on the branch invoking the + fsyscall-handler, at which point, by definition, a syscall + restart is still safe. If the system call number is invalid, + the fsys-mode handler will return directly to user-level. This + return will trigger a taken-branch trap, but since the trap is + taken _after_ restoring the privilege level, the CPU has already + left fsys-mode, so no special treatment is needed. +PSR.rt Unchanged. +PSR.cpl Cleared to 0. +PSR.is Unchanged (guaranteed to be 0 on entry to the gate page). +PSR.mc Unchanged. +PSR.it Unchanged (guaranteed to be 1). +PSR.id Unchanged. Note: the ia64 linux kernel never sets this bit. +PSR.da Unchanged. Note: the ia64 linux kernel never sets this bit. +PSR.dd Unchanged. Note: the ia64 linux kernel never sets this bit. +PSR.ss Lazy redirect. If set, "epc" will cause a Single Step Trap to + be taken. The trap handler then modifies the saved machine + state such that execution resumes in the gate page at + syscall_via_break(), with privilege level 3. +PSR.ri Unchanged. +PSR.ed Unchanged. Note: This bit could only have an effect if an fsys-mode + handler performed a speculative load that gets NaTted. If so, this + would be the normal & expected behavior, so no special treatment is + needed. +PSR.bn Unchanged. Note: fsys-mode handlers may clear the bit, if needed. + Doing so requires clearing PSR.i and PSR.ic as well. +PSR.ia Unchanged. Note: the ia64 linux kernel never sets this bit. + +* Using fast system calls + +To use fast system calls, userspace applications need simply call +__kernel_syscall_via_epc(). For example + +-- example fgettimeofday() call -- +-- fgettimeofday.S -- + +#include <asm/asmmacro.h> + +GLOBAL_ENTRY(fgettimeofday) +.prologue +.save ar.pfs, r11 +mov r11 = ar.pfs +.body + +mov r2 = 0xa000000000020660;; // gate address + // found by inspection of System.map for the + // __kernel_syscall_via_epc() function. See + // below for how to do this for real. + +mov b7 = r2 +mov r15 = 1087 // gettimeofday syscall +;; +br.call.sptk.many b6 = b7 +;; + +.restore sp + +mov ar.pfs = r11 +br.ret.sptk.many rp;; // return to caller +END(fgettimeofday) + +-- end fgettimeofday.S -- + +In reality, getting the gate address is accomplished by two extra +values passed via the ELF auxiliary vector (include/asm-ia64/elf.h) + + o AT_SYSINFO : is the address of __kernel_syscall_via_epc() + o AT_SYSINFO_EHDR : is the address of the kernel gate ELF DSO + +The ELF DSO is a pre-linked library that is mapped in by the kernel at +the gate page. It is a proper ELF shared object so, with a dynamic +loader that recognises the library, you should be able to make calls to +the exported functions within it as with any other shared library. +AT_SYSINFO points into the kernel DSO at the +__kernel_syscall_via_epc() function for historical reasons (it was +used before the kernel DSO) and as a convenience. diff --git a/Documentation/ia64/serial.txt b/Documentation/ia64/serial.txt new file mode 100644 index 00000000000..f51eb4bc2ff --- /dev/null +++ b/Documentation/ia64/serial.txt @@ -0,0 +1,144 @@ +SERIAL DEVICE NAMING + + As of 2.6.10, serial devices on ia64 are named based on the + order of ACPI and PCI enumeration. The first device in the + ACPI namespace (if any) becomes /dev/ttyS0, the second becomes + /dev/ttyS1, etc., and PCI devices are named sequentially + starting after the ACPI devices. + + Prior to 2.6.10, there were confusing exceptions to this: + + - Firmware on some machines (mostly from HP) provides an HCDP + table[1] that tells the kernel about devices that can be used + as a serial console. If the user specified "console=ttyS0" + or the EFI ConOut path contained only UART devices, the + kernel registered the device described by the HCDP as + /dev/ttyS0. + + - If there was no HCDP, we assumed there were UARTs at the + legacy COM port addresses (I/O ports 0x3f8 and 0x2f8), so + the kernel registered those as /dev/ttyS0 and /dev/ttyS1. + + Any additional ACPI or PCI devices were registered sequentially + after /dev/ttyS0 as they were discovered. + + With an HCDP, device names changed depending on EFI configuration + and "console=" arguments. Without an HCDP, device names didn't + change, but we registered devices that might not really exist. + + For example, an HP rx1600 with a single built-in serial port + (described in the ACPI namespace) plus an MP[2] (a PCI device) has + these ports: + + pre-2.6.10 pre-2.6.10 + MMIO (EFI console (EFI console + address on builtin) on MP port) 2.6.10 + ========== ========== ========== ====== + builtin 0xff5e0000 ttyS0 ttyS1 ttyS0 + MP UPS 0xf8031000 ttyS1 ttyS2 ttyS1 + MP Console 0xf8030000 ttyS2 ttyS0 ttyS2 + MP 2 0xf8030010 ttyS3 ttyS3 ttyS3 + MP 3 0xf8030038 ttyS4 ttyS4 ttyS4 + +CONSOLE SELECTION + + EFI knows what your console devices are, but it doesn't tell the + kernel quite enough to actually locate them. The DIG64 HCDP + table[1] does tell the kernel where potential serial console + devices are, but not all firmware supplies it. Also, EFI supports + multiple simultaneous consoles and doesn't tell the kernel which + should be the "primary" one. + + So how do you tell Linux which console device to use? + + - If your firmware supplies the HCDP, it is simplest to + configure EFI with a single device (either a UART or a VGA + card) as the console. Then you don't need to tell Linux + anything; the kernel will automatically use the EFI console. + + (This works only in 2.6.6 or later; prior to that you had + to specify "console=ttyS0" to get a serial console.) + + - Without an HCDP, Linux defaults to a VGA console unless you + specify a "console=" argument. + + NOTE: Don't assume that a serial console device will be /dev/ttyS0. + It might be ttyS1, ttyS2, etc. Make sure you have the appropriate + entries in /etc/inittab (for getty) and /etc/securetty (to allow + root login). + +EARLY SERIAL CONSOLE + + The kernel can't start using a serial console until it knows where + the device lives. Normally this happens when the driver enumerates + all the serial devices, which can happen a minute or more after the + kernel starts booting. + + 2.6.10 and later kernels have an "early uart" driver that works + very early in the boot process. The kernel will automatically use + this if the user supplies an argument like "console=uart,io,0x3f8", + or if the EFI console path contains only a UART device and the + firmware supplies an HCDP. + +TROUBLESHOOTING SERIAL CONSOLE PROBLEMS + + No kernel output after elilo prints "Uncompressing Linux... done": + + - You specified "console=ttyS0" but Linux changed the device + to which ttyS0 refers. Configure exactly one EFI console + device[3] and remove the "console=" option. + + - The EFI console path contains both a VGA device and a UART. + EFI and elilo use both, but Linux defaults to VGA. Remove + the VGA device from the EFI console path[3]. + + - Multiple UARTs selected as EFI console devices. EFI and + elilo use all selected devices, but Linux uses only one. + Make sure only one UART is selected in the EFI console + path[3]. + + - You're connected to an HP MP port[2] but have a non-MP UART + selected as EFI console device. EFI uses the MP as a + console device even when it isn't explicitly selected. + Either move the console cable to the non-MP UART, or change + the EFI console path[3] to the MP UART. + + Long pause (60+ seconds) between "Uncompressing Linux... done" and + start of kernel output: + + - No early console because you used "console=ttyS<n>". Remove + the "console=" option if your firmware supplies an HCDP. + + - If you don't have an HCDP, the kernel doesn't know where + your console lives until the driver discovers serial + devices. Use "console=uart, io,0x3f8" (or appropriate + address for your machine). + + Kernel and init script output works fine, but no "login:" prompt: + + - Add getty entry to /etc/inittab for console tty. Look for + the "Adding console on ttyS<n>" message that tells you which + device is the console. + + "login:" prompt, but can't login as root: + + - Add entry to /etc/securetty for console tty. + + + +[1] http://www.dig64.org/specifications/DIG64_PCDPv20.pdf + The table was originally defined as the "HCDP" for "Headless + Console/Debug Port." The current version is the "PCDP" for + "Primary Console and Debug Port Devices." + +[2] The HP MP (management processor) is a PCI device that provides + several UARTs. One of the UARTs is often used as a console; the + EFI Boot Manager identifies it as "Acpi(HWP0002,700)/Pci(...)/Uart". + The external connection is usually a 25-pin connector, and a + special dongle converts that to three 9-pin connectors, one of + which is labelled "Console." + +[3] EFI console devices are configured using the EFI Boot Manager + "Boot option maintenance" menu. You may have to interrupt the + boot sequence to use this menu, and you will have to reset the + box after changing console configuration. |